In a manufacturing process of a semiconductor device, there is a liquid processing that removes particles or pollutants attached to a wafer W by supplying chemical liquid or deionized water onto the surface of a target object, such as a semiconductor wafer (“wafer W”). A liquid processing apparatus is known to perform a liquid processing by supplying a processing liquid onto the surface of a wafer W while rotating wafer W. In the liquid processing apparatus, in order to increase the number of processed wafer W per unit time (throughput), a plurality of liquid processing units (e.g., four to five liquid processing units) that can perform the same kind of liquid processing are provided and wafers W are transferred between the processing units by a common transfer mechanism, such that the liquid processing is simultaneously performed in the plurality of liquid processing units.
The liquid processing unit as shown in FIG. 16 includes a spin chuck 11 that rotates a wafer W having placed thereon, and a cup 12 that surrounds wafer W on spin chuck 11. Acidic or alkaline chemical liquids are used as the processing liquid, and the chemical liquids are switched from a nozzle (not shown) and supplied to wafer W in accordance with the processing.
Japanese Patent Laid-Open Publication No. 2008-34490 (e.g., paragraph [0034], FIGS. 4 and 6), discloses a configuration in which a plurality of liquid processing units are arranged horizontally and an exclusive exhaust line is provided for each of the acidic or alkaline chemical liquid. In this configuration, as shown in FIG. 16, cup 12 of each of liquid processing units is connected with exhaust line 13 of acidic chemical liquid and exhaust line 14 of alkaline chemical liquid, respectively, by exclusive exhaust paths 15 and 16. Valves V15 and V16 are disposed in exhaust paths 15 and 16, respectively, and the atmosphere inside cup 12 is discharged through exclusive exhaust lines 13 and 14 by opening/closing valves V15 and V16 in accordance with the chemical liquid.
However, in this configuration, valves V15 and V16 are required for exclusive exhaust paths 15 and 16, and the number of valves to be equipped is increased as the kind of chemical liquids increases. Further, as the number of valves increases, the number of driving units for the valves increases, such that the control time and the spaces being occupied by the valves or driving units increase.